Gas turbines coupled to generators are used for converting fossil energy into electrical energy. To this end, a gas turbine has a compressor, a combustion chamber and a turbine unit along its rotor shaft. During operation of the gas turbine, the compressor draws in ambient air and compresses it. The compressed air is then mixed with a fuel and fed to the combustion chamber. There, the gas burns to form a hot working medium and then flows into the turbine unit, in which blades are provided. In the process, the guide blades fastened to the casing of the turbine unit guide the working medium onto the moving blades fastened to the rotor, so that said moving blades set the rotor in a rotary movement. The rotational energy thus absorbed is then converted into electrical energy by the generator coupled to the rotor. Furthermore, it is used for driving the compressor.
WO 00/28190 discloses a gas turbine having a compressor, the rotor of which is displaced against the direction of flow of the working medium in order to set the radial gap which is formed between the tips of the turbine moving blades and the inner casing. In the process, the radial gaps of the turbine unit are reduced, which leads to a substantial reduction in the flow losses in the turbine unit and therefore to an increase in the efficiency of the gas turbine. At the same time, the radial gaps in the compressor are increased, which increases the flow losses in the compressor. Despite the losses in the compressor, the displacement of the rotor leads to an increase in the output of the gas turbine.
Furthermore, U.S. Pat. No. 5,056,986 discloses a gas turbine having a compressor in which rings of guide blades and moving blades are alternately arranged one behind the other. The guide blades are secured on the tip side in a fastening ring enclosing the rotor, and the moving blades are each provided with shroud bands which form a shroud-band ring on the tip side, this shroud-band ring being opposite the casing, with a radial gap being formed. In this case, the radial gaps run parallel to the rotation axis.